1. Field of the Invention
The present invention relates to an imaging unit and imaging module that include an imaging device and an optical member.
2. Description of the Related Art
Conventionally, electronic imaging modules supporting various types from a digital camera and a digital video camera to a mobile phone with an imaging function and to an endoscope system for observing the inside of an organ of a subject have appeared. Among them, the endoscope system includes an imaging unit where an imaging device is implemented on a distal end section of a slim and long insertion tool having flexibility. The insertion tool is inserted into the body cavity to perform things such as observing a region to be examined.
The imaging unit includes the imaging device such as a CCD image sensor or a CMOS image sensor, forms an optical image of an object on a light receiving unit of the imaging device by an optical system such as a lens, and captures the image data of the object by an photoelectric conversion process of the imaging device.
Conventionally the endoscope apparatus has been required to downsize the diameter of the distal end section of the insertion tool to reduce a burden on the subject. In recent years, an imaging unit was proposed where a prism is mounted on an imaging device placed substantially parallel to the optical axis of an objective lens system so as to ensure a sufficient light receiving area on the imaging device even if the area of a vertical plane with respect to the optical axis, the area being available for the imaging unit, is reduced due to the downsizing of the diameter of the distal end section of the insertion tool (see, for example, Japanese Laid-open Patent Publication No. 8-106055).